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在高层次上,我创建了一个应用程序,让用户可以指向他或她的iPhone相机并查看已经过视觉效果处理过的视频帧.此外,用户可以点击按钮将当前预览的定格作为保存在其iPhone库中的高分辨率照片.

为此,该应用程序遵循以下过程:

1)创建AVCaptureSession

captureSession = [[AVCaptureSession alloc] init];
[captureSession setSessionPreset:AVCaptureSessionPreset640x480];

2)使用后置摄像头连接AVCaptureDeviceInput.

videoInput = [[[AVCaptureDeviceInput alloc] initWithDevice:backFacingCamera error:&error] autorelease];
[captureSession addInput:videoInput];

3)将AVCaptureStillImageOutput连接到会话,以便能够以Photo分辨率捕获静止帧.

stillOutput = [[AVCaptureStillImageOutput alloc] init];
[stillOutput setOutputSettings:[NSDictionary
    dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
    forKey:(id)kCVPixelBufferPixelFormatTypeKey]];
[captureSession addOutput:stillOutput];

4)将AVCaptureVideoDataOutput连接到会话,以便能够以较低分辨率捕获单个视频帧(CVImageBuffers)

videoOutput = [[AVCaptureVideoDataOutput alloc] init];
[videoOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];
[videoOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
[captureSession addOutput:videoOutput];

5)在捕获视频帧时,将每个新帧作为CVImageBuffer调用委托的方法:

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    [self.delegate processNewCameraFrame:pixelBuffer];
}

6)然后委托处理/绘制它们:

- (void)processNewCameraFrame:(CVImageBufferRef)cameraFrame {
    CVPixelBufferLockBaseAddress(cameraFrame, 0);
    int bufferHeight = CVPixelBufferGetHeight(cameraFrame);
    int bufferWidth = CVPixelBufferGetWidth(cameraFrame);

    glClear(GL_COLOR_BUFFER_BIT);

    glGenTextures(1, …